1. Technical Field
The invention relates to a hydrodynamic axial bearing with floating disk according to the preamble of patent claim 1.
2. Prior Art
In order to improve the skew compensation capacity and the wear behavior in hydrodynamic axial bearings, for example of turbochargers, what are known as floating disks may be inserted between the bearing collar rotating at the shaft rotational speed and the nonrotating casing. Examples of this are found, inter alia, in U.S. Pat. No. 1,786,565 and GB-1,095,999. The radial guidance of the floating disk takes place on the rotating body, that is to say on the shaft or on the bearing collar, by means of a radial bearing integrated into the floating disk, as disclosed, for example, in DE-A-196 41 673. The lubrication of such a hydrodynamic axial bearing is carried out, as a rule, by means of lubricating oil from a specific lubricating-oil system or, in the case of turbochargers, via the lubricating-oil system of an internal combustion engine connected to the turbocharger.
During operation, a load-bearing lubricating-oil film builds up between the floating disk rotating at only about half the rotor rotational speed and the shaft or the bearing collar. In the case of pronounced radial oscillations of the shaft, for example due to unbalance, however, overloading of the radial bearing of the floating disk and wear in the radial bearing of the floating disk may occur.
The object of the present invention is, therefore, to provide a hydrodynamic axial bearing with floating disk, in which overloading of the radial bearing of the floating disk is largely ruled out.
This object is achieved by means of a hydrodynamic axial bearing according to the features of patent claim 1.
By means of the radial mounting of a floating disk on a fixed bearing element concentrically surrounding the rotating body of an axial bearing, oscillations and jolts of the rotating body in the uncoupling gap between the bearing element and the rotating body are intercepted and kept away from the radial bearing of the floating disk. Overloading of the radial bearing and wear in the radial bearing of the floating disk are thereby avoided.
A one-piece version of the bearing element and bearing body is highly advantageous, since this makes particularly simple and cost-effective production possible.
However, a two-part design of the bearing element and bearing body may also be advantageous when the bearing body is manufactured, for example, as a casting and the bearing element is to acquire high wear resistance by virtue of a special choice of material or surface treatment.
In such a case, a fixed and releasable connection between the bearing element and bearing body is highly advantageous, since it simplifies the production and assembly of the hydrodynamic axial bearing.
A press fit is highly suitable as a fixed connection between the bearing element and bearing body. The press fit ensures that the bearing element is fixed in relation to the rotating body and to the rotating floating disk and is simple in terms of production and reliable during operation.
The bearing element has, for the press fit, a fitting part held in the press seat. It is particularly advantageous for the fitting part to be provided with a recess. The bearing element can thereby be fitted more simply into the press seat, and the deformation of the bearing element in the region of the bearing seat, this being caused by the press fit, can be kept low. The recess may at the same time be utilized highly advantageously as a lubricating-oil reservoir for the lubrication of the floating disk.
It is particularly advantageous to provide a closed bush as bearing element, in order largely to avoid a reduction in the uncoupling properties due to lubricating oil in the uncoupling gap.
The uncoupling gap between the bearing element and the rotating body may advantageously be produced in the form of a wide tolerance gap. Lubricating oil penetrating into the uncoupling gap then cannot reduce the uncoupling properties.
The bearing element may advantageously be designed in such a way that lubricating oil passes via the bearing element into the radial bearing of the floating disk and into the lubricating gaps surrounding the latter.
For this purpose, for example, the bearing element may be connected conductively to a lubricating-oil feed and that surface of the bearing body which cooperates with the floating disk may be profiled in such a way that a connection permeable to the lubricating oil is made between the lubricating-oil gaps via this profile. Such a profile may be designed in such a way that it functions as a hydrodynamic radial bearing for the floating disk and the floating disk itself does not need to have an integrated radial bearing.
Moreover, connecting orifices may be provided in the bearing body, which issue into the radial bearing and the lubricating gaps and are connected to a lubricating-oil feed line, so that the lubricating oil can be fed directly into the lubricating-oil gaps and the radial bearing. These connecting orifices may be provided, in addition to the profile or else without a profile, on the outside of the bearing element.
Further preferred embodiments of the hydrodynamic axial bearing are the subject matter of further dependent patent claims.